1. Field of the Invention
The present invention relates to a tape guiding mechanism for guiding a tape such as a magnetic tape, a magnetic tape apparatus for reading/writing a magnetic tape, and a method for manufacturing a magnetic tape.
2. Description of the Related Art
High density writing has recently advanced with regard to magnetic tapes, and some magnetic tapes used for backing up computers have a storage capacity of approximately 400 giga bytes. For this purpose, magnetic tape has several hundred data tracks formed in its width direction. Accordingly, the width of each data track is very narrow, and the interval between adjacent data tracks is also narrow. For this reason, in order to make the reading/writing element of a magnetic head trace the data track, its position (the position of the magnetic tape in its width direction) is servo-controlled by pre-written servo signals on the magnetic tape, which are read by the magnetic head.
Also, as shown in FIG. 10, as a servo writer for writing the a servo signal on the magnetic tape, there exists a servo writer 100 including a magnetic tape transport system in which a magnetic tape MT fed from a feed reel 11 is taken up by a take-up reel 12 to thereby travel, a servo signal writing head 16 for writing a servo signal on the magnetic tape MT, and a tension adjuster 13 for adjusting a tension of the traveling magnetic tape MT, (see Japanese published unexamined patent application No. 2005-259239, for instance).
The tension adjuster 13 provides a longitudinal directional tension to the magnetic tape MT to prevent the traveling magnetic tape MT from swaying, and may have a configuration in which the longitudinal directional tension is provided to the magnetic tape MT by, for example, vacuuming a portion of the traveling magnetic tape MT, or moving a tension roller, on which the magnetic tape MT travels, to thereby draw in a portion of the magnetic tape.
Also, the conventional servo writer 100 described above is provided with a plurality of guide rollers 19 for guiding the traveling magnetic tape MT. Each of the guide rollers 19 includes a cylindrical roller body with a circumferential surface for guiding the traveling magnetic tape MT, and is arranged between the feed reel 11 and the take-up reel 12.
In the conventional servo writer 100 described above, an edge of the traveling magnetic tape MT rubs against flange parts of the guide rollers 19 so that the traveling position of the magnetic tape MT is regulated. Thus, if the edge of the magnetic tape MT is curved in its longitudinal direction, the magnetic tape MT sways in a width direction of the tape along the curvature of the edge. Consequently, written servo signals deviate in the width direction of the tape, so as to increase a PES (Position Error Signal) which indicates fluctuation of a displacement amount of the signal written on the magnetic tape MT. This then causes a servo signal read error in a magnetic tape reader/writer, resulting in a problem of being unable to accurately regulate the position of the magnetic head.
Also in the conventional servo writer 100 described above, the edge of the traveling magnetic tape MT scrapes against a part of the tension adjuster 13, thereby causing vibrations of the magnetic tape MT. Then, vibrations of the magnetic tape MT which occur in the tension adjuster 13 are propagated in its longitudinal direction, and the effect of vibrations causes a longitudinal directional fluctuation in the servo signals written on the magnetic tape MT.
Furthermore, in each of the guide rollers 19 for guiding the magnetic tape MT to travel, air flowing around the traveling magnetic tape MT (hereinafter also referred to as “accompanying air”) intrudes between the magnetic tape MT and the roller body, and the accompanying air then causes an air layer between the magnetic tape MT and the roller body, whereby the magnetic tape MT travels while floating above the circumferential surface of the roller body. Thus, the traveling magnetic tape MT does not come into contact with the roller body of the guide rollers 19, whereby the magnetic tape MT is likely to sway in the width direction of the tape on the circumferential surface of the roller body, and vibrations which occur in the magnetic tape MT pass through a part guided by the guide rollers 19 to be thereby propagated in the longitudinal direction of the magnetic tape MT.
It is therefore an objective of the present invention to solve the above-described problems and provide a tape guiding mechanism with which a tape can stably travel in the appropriate position and propagation of vibrations which occur in the traveling tape can be prevented.
Another objective is to provide a magnetic tape apparatus capable of accurately writing a signal or data on a magnetic tape, or accurately reading a signal or data from the magnetic tape.
Still another objective is to provide a method for manufacturing a magnetic tape that enables a servo signal to be accurately written on the magnetic tape.